کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
2073148 | 1544759 | 2012 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Stimulation of a pulse of LH and reduction in PRL concentration by a physiologic dose of GnRH before, during, and after luteolysis in heifers
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موضوعات مرتبط
علوم زیستی و بیوفناوری
علوم کشاورزی و بیولوژیک
علوم دامی و جانورشناسی
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چکیده انگلیسی
A single physiologic dose (5.0 μg) of GnRH was given to 9 heifers each day (Hour 0) beginning on Day 15 postovulation until regression of the corpus luteum. Blood samples were taken each day for Hours â3, â2, â1, 0, 0.25, 0.5, 0.75, 1, 1.25, 1.50, 1.75, 2, 3, 4, and 5. Based on daily progesterone concentrations, data were grouped into phases of before (n = 4), during (n = 8), and after (n = 7) luteolysis. The number of LH pulses with a peak at pretreatment Hours â2 or â1 (0.35 ± 0.12 pulses/sampling session) was less (P < 0.0001) than for a pulse peak at posttreatment Hours 1 or 2 (1.0 ± 0.0 pulses/session). The characteristics and effects of LH pulses on progesterone and estradiol were similar between natural (pretreatment) and primarily induced (posttreatment) LH pulses. The same dose of GnRH stimulated an LH pulse with greater (P < 0.05) amplitude after luteolysis than during luteolysis. Concentrations of PRL and number and prominence of PRL pulses decreased (P < 0.05) between Hours 0 and 2 within each of the phases of before, during, and after luteolysis. The hypothesis that a physiologic dose of GnRH increases the concentration of PRL was not supported; instead, GnRH reduced the concentration of PRL. Results supported the hypotheses that an appropriate dose of GnRH stimulates an LH pulse during luteolysis that is similar to a natural pulse in characteristics and in the effects on progesterone and estradiol.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Animal Reproduction Science - Volume 133, Issues 1â2, July 2012, Pages 52-62
Journal: Animal Reproduction Science - Volume 133, Issues 1â2, July 2012, Pages 52-62
نویسندگان
O.J. Ginther, M.A. Beg,